Homogeneous polymerization process for making substantially homogeneous terpolymers

ABSTRACT

A homogeneous polymerization process is described for making substantially homogeneous terpolymers of, by weight, 55-99%, preferably 65-95% of vinyl pyrrolidone; 0.5-49%, preferably 1-25% of a quaternary amino monomer, preferably 3-methacrylamidopropyl trimethylammonium chloride; and 0.5-49%, preferably 1-25%, of a hydrophobic monomer, preferably octadecyl methacrylate. The homogeneous terpolymer provides dual hair styling and conditioning functions in hair care applications.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a process for making substantially homogeneousterpolymers of vinyl pyrrolidone, a quaternary amino monomer and ahydrophobic monomer, for use in hair care applications.

2. Description of the Prior Art

Several synthetic polymers containing vinyl lactams are presently beingused in cosmetic formulations, particularly in hair care products, tocontribute body, set retention and conditioning to such products.

Representative of the art in this field are the following U.S. Pat Nos.:3,914,403; 3,954,960; 4,057,533; 4,210,161; 4,586,518; 4,753,793;4,764,363; 4,834,968; 4,842,850; 4,902,499; 4,906,459; 4,923,694;4,963,348; 4,983,377; 5,011,895 and 5,015,708; and WO 91/15186; WO91/15185; EPO 0412704A2; EPO 0412707A1; and JP 57126409.

These synthetic polymers generally are made by a "one-pot"polymerization process in which selected amounts of the several monomersare reacted together. The composition of the thus-formed polymer isconsidered as being the same as the composition of the charged monomers.However, such conventional non-homogeneous polymerization processes canprovide only a mixture of polymers of various compositions, and,additionally, an indeterminate amount of homopolymers and undesiredcopolymers.

Accordingly, it is an object of this invention to provide a homogeneouspolymerization process for making substantially homogeneous copolymersof vinyl pyrrolidone, a quaternary amino monomer and a hydrophobicmonomer.

Another object of this invention is to provide a clear, aqueous solutionof substantially homogeneous terpolymers of vinyl pyrrolidone (VP),3-methacrylamidopropyl trimethylammonium chloride (MAPTAC), and RMAwhere R is C₄ -C₃₂, and MA is methacrylate, preferably octadecylmethacrylate (ODMA), in a compositional range, by weight, of 55-99% VP,0.5-49% MAPTAC and 0.5-49% ODMA.

Still another object herein is to provide clear, aqueous solutions ofsubstantially homogeneous terpolymers of VP, MAPTAC and RMA in apredetermined compositional range and at a selected solids level, which,upon formulation into hair styling and conditioning compositions, willprovide enhanced water solubility, and improved fixative, conditioning,and hair holding properties for the user.

SUMMARY OF THE INVENTION

A homogeneous polymerization process is described for makingsubstantially homogeneous terpolymers comprising, by weight, 55-99%,preferably 65-95% of vinyl pyrrolidone, 0.5-49%, preferably 1-25% of aquaternary amino monomer, preferably 3-methacrylamidopropyltrimethylammonium chloride; and 0.5-49%, preferably 1-25%, of ahydrophobic monomer, preferably RMA, where R is C₄ -C₃₂ alkyl, and, mostpreferably, octadecyl methacrylate.

Such homogeneous terpolymers provide both hair styling and conditioningfor the user. The homogeneous terpolymer solution herein also has betterclarity, and provides hair care products with greater water solubility,and improved polymer adsorption onto hair, when compared tonon-homogeneous copolymers of the same composition, or related existingcommercial products.

The homogeneous polymerization process of the invention includesprecharging VP, and solvent, and introducing the MAPTAC and ODMAmonomers incrementally at rates corresponding to the rate ofdisappearance of VP, over a given period of time.

IN THE DRAWINGS

FIG. 1 is a graphical representation of a conventional non-homogeneous("one-pot") polymerization process for making a terpolymer ofvinylpyrrolidone (VP), 3-methacrylamidopropyl trimethylammonium chloride(MAPTAC), and octadecyl methacrylate (ODMA) monomers from prechargedamounts of the monomers. The relative monomer content of each monomerremaining during the polymerization is plotted vs. time.

FIG. 2 is a graphical representation of the homogeneous process of theinvention for making the same terpolymer.

DETAILED DESCRIPTION OF THE INVENTION A. TERPOLYMER OF INVENTION

1. Hydrophilic Monomers

(a) Lactam Monomer

Vinylpyrrolidone is the most preferred vinyl lactam.

The vinyl lactam monomer is present in an amount of about 55-99%, and,preferably, 65-95%, by weight of the terpolymer.

(b) Quaternary Amino Acrylamide or Acrylate Monomer

The quaternary amino acrylamide or acrylate monomer in the terpolymer ofthe invention has the formula: ##STR1## where Y is O or --NX--;

R is C₂ -C₂₀ alkyl or ##STR2## where n is 0-10,

X and X₁ are independently H, or C₁ to C₈ alkyl;

R₁, R₂ and R₃ are independently C₁ -C₄ alkyl; and

Z is a halide, sulfate or sulfonate.

Suitable examples of amino acrylamides, acrylates, methacrylamides, ormethacrylates which are employed as monomers in the terpolymer of theinvention include quaternized salts of

N-[12-(dimethylamino)dodecyl] methacrylamide or methacrylate;

N-[18-(dimethylamino) octadecyl] methacrylamide or methacrylate;

N-[8-(dimethyl-amino)octyl]methacrylamide or methacrylate;

N-[7-(dimethylamino)heptyl]acrylamide or acrylate;

N-[14-(dimethylamino)tetradecyl]acrylamide or acrylate;

N-[3-(dimethylamino)propyl]methacrylamide or methacrylate;

N-[3-(diethylamino)propyl]acrylamide or acrylate;

N-[4-(dipropylamino)butyl]methacrylamide or methacrylate;

N-[3-(methyl butyl amino)propyl]acrylamide or acrylate;

N-{2-[3-(dimethylamino)propyl]ethyl}acrylamide or acrylate; and

N-{4-[4-(diethylamino)butyl] butyl}acrylamide or acrylate.

Of the above group, the

N-[(dimethylamino)alkyl]methacrylamides or acrylamides, methacrylatesand acrylates of their quaternized halide, sulfate and sulfonate saltsare preferred. Of these, 2-(ethyl dimethylammonium) ethyl methacrylatesulfate; (3-methacrylamidopropyl) trimethylammonium chloride (MAPTAC);(3-acrylamido-3-methylbutyl)propyl trimethylammonium bromide;(3-methacrylamido-3-ethyl-butyl)propyl trimethylammonium chloride;(4-acrylamido-n-methylbutyl)propyl trimethylammonium chloride; and(3-methacrylamidopropyl) ethyl dimethylammonium ethyl sulfate, or amixture thereof, are most preferred. Where the quaternized aminoacrylamide is (3-methacrylamidopropyl)trimethylammonium chloride, theformula is represented by X and X₁ being CH₃ ; Y being NH; R being C₃alkyl; R₁, R₂ and R₃ being methyl; and Z being chloride.

The quaternary amino monomer suitably is present in the terpolymer in anamount of about 0.5-49%, and, preferably 1-25%, by weight of theterpolymer.

The vinyl lactam and quaternary amino acrylamide or acrylate monomersconstitute the hydrophilic portion of the terpolymer of the invention.

2. Hydrophobic Monomer

The hydrophobic monomer in the terpolymer of the invention suitably hasthe formula: RMA where R is a C₄ -C₃₂ alkyl, preferably C₁₂ -C₃₂ alkyl,or a mixture thereof; and MA is an acrylate, methacrylate, acrylamide ormethacrylamide. Suitable hydrophobic monomers include 2-ethylhexylmethacrylate, dodecyl acrylate, tetradecyl acrylate, octadecylmethacrylate (ODMA), octadecyl methacrylamide, dodecyl acrylamide and2-ethylhexyl methacrylamide. A preferred hydrophobic monomer isoctadecyl methacrylate.

The hydrophobic monomer is present in an amount of about 0.5-49%,preferably 1-25%, by weight of the terpolymer.

B. HOMOGENEOUS POLYMERIZATION

The homogeneous polymerization process of the invention is illustratedby making substantially homogeneous terpolymers of VP, MAPTAC and ODMAin a predetermined composition.

In the homogeneous process, the least reactive monomer of the terpolymer(VP) is precharged into a reactor at a suitable reaction temperature,generally about 50°-80° C., and preferably 55°-75° C. The more reactivemonomers (MAPTAC and ODMA) then are introduced incrementally into theVP-charged reactor at a rate which corresponds to the observed rate ofdisappearance of VP, over the period of polymerization.

The entire predetermined amount of the MAPTAC and ODMA monomers areadded before substantially all the VP monomer has been consumed so thatall monomers can react to form a substantially homogeneous terpolymer ina desired compositional ratio of VP:MAPTAC:ODMA. Consequently, asubstantially homogeneous terpolymer is obtained whose compositionapproaches the nominal monomer ratio of the desired terpolymercomposition and whose structure has the three individual monomeric unitsof the copolymer distributed substantially uniformly in a homogeneouschain along the backbone of the polymer.

The precharge in the process of the invention may include some MAPTACand ODMA therein, generally in an amount of up to about 15% of the totalamount of MAPTAC and ODMA required for a predetermined terpolymercomposition without affecting the homogeneous polymerization process.However, it is still necessary that the rate of addition of MAPTAC andODMA after any precharge be carried out at substantially the rate ofdisappearance of VP during polymerization.

The schedule of addition of MAPTAC and ODMA to accomplish the desiredmatched rate of reaction of VP is determined in the following manner.

DETERMINATION OF ADDITION SCHEDULES FOR MAPTAC AND ODMA TO FORM AHOMOGENEOUS TERPOLYMER WITH VP

A. First, a one-pot polymerization of VP, MAPTAC and ODMA monomers iscarried out as follows:

EXAMPLE 1

VP (553.5 g), MAPTAC (124.5 g), ODMA (95.6 g) and ethanol (753.5 g) werecharged into a 2-liter resin pot equipped with a gas inlet, a liquidinlet, a thermometer and a condenser. The pH of the solution wasadjusted to about 7.5 with KOH. A stream of nitrogen then was bubbledthrough the solution during the reaction. The solution was graduallyheated to 68° C., and 0.25 ml of Lupersol 11 as catalyst was added; thenanother 0.25 ml of the catalyst was added after 10 minutes; and another6 units of 0.25 ml amount was added each 30 minutes. The reaction wascarried out for an additional 3 hours.

The relative percentage amounts of residual monomers present during thecourse of the one-pot reaction was determined by gas chromatographicanalysis after sampling the reaction mixture periodically. Theanalytical data obtained then was plotted as the graph of FIG. 1.

As shown in FIG. 1, the MAPTAC and ODMA monomers react much more rapidlythan VP. Accordingly, after 100 minutes, for example, all the MAPTAC andODMA monomers are consumed while residual VP monomer still is availablefor homopolymerization. Thus the terpolymer formed is of a compositiondifferent from the desired monomer ratios selected by the prechargedamounts of the two monomers. Under these experimental conditions, thepolymer product obtained is a complex mixture of a homopolymer which ispolyvinylpyrrolidone, various copolymers, and a terpolymer of theseveral monomers of uncertain composition.

B. To form a homogeneous terpolymer, it is necessary that the curve ofrate of reaction vs. time for both MAPTAC and ODMA substantiallycoincide or match the rate of reaction curve for VP. To accomplish this,the VP is precharged and substantially all the MAPTAC and RMA monomersare fed external to the precharge at a feeding schedule determined byanalysis of the data of FIG. 1. The % MAPTAC and ODMA monomers to be fedat time t of the polymerization is determined from the Asymmetric DoubleSigmoidal Distribution formula, A_(t), below, which has four adjustableparameters, a₁, a₂, a₃ and a₄ : ##EQU1## where

t=where time in minutes during copolymerization;

a₁ is a parameter which determines the center of the distribution;

a₂ is a parameter which affects the width of the distribution;

a₃ is a parameter which determines the ascending portion of thedistribution; and

a₄ is a parameter which determines the descending portion of thedistribution. ##EQU2## where

N=time when the polymerization is completed.

To match the MAPTAC and ODMA curves to the VP curve of FIG. 1, an"initial guess" is made for the values of a₁, a₂, a₃ and a₄ for each ofthese monomers. Then these values are inserted into the A_(t) formulaand the % MAPTAC and ODMA to be fed at time t is calculated. Theresulting % unreacted MAPTAC and ODMA during this polymerization willprobably not match the % unreacted VP at the same time t. If the %unreacted MAPTAC or ODMA at time t is too large, then the value of a₃(ascendency) in the A_(t) formula is increased, a₄ (descendency) isdecreased, a₁ (center) is decreased, and a₂ (width) is decreased.Conversely, if the initial guess values of a₁ through a₄ give a reactionrate for MAPTAC or ODMA which is too fast, then changes in the values ofa₁ through a₄ are made in a direction opposite to those discussed above.

These new values of the parameters are then used to determine a newfeeding schedule. Using this feeding schedule, another polymerization iscarried out, and the process of adjustment of the parameters describedabove is repeated.

This process is known as "interative fitting" of data to a curve. After4 or 5 such iterative fittings, the experimental VP, MAPTAC and ODMAcurves will be matched, as shown in FIG. 2 herein.

The matched curves of VP, MAPTAC and ODMA in FIG. 2 will have at leastone set of values for a₁, a₂, a₃ and a₄ (the last set of the iterativefitting process) for suitable feeding of MAPTAC and ODMA over the entireperiod of polymerization. One such set is:

    ______________________________________                                        MAPTAC        ODMA                                                            ______________________________________                                        a.sub.1 = 41  a.sub.1 = 56                                                    a.sub.2 = 82  a.sub.2 = 90                                                    a.sub.3 = 10  a.sub.3 = 10                                                    a.sub.4 = 79  a.sub.4 = 67                                                    ______________________________________                                    

C. With such schedules available, a homogeneous terpolymer of VP, MAPTACand ODMA can be prepared as described in Example 2 below.

EXAMPLE 2

Preparation of a Homogeneous Terpolymer of VP, MAPTAC and ODMA

VP (303.6 g), MAPTAC (7.8 g), ODMA (3.1 g), and ethanol (1001.0 g) arecharged into a 2-liter resin pot equipped with a gas inlet, a liquidinlet, a thermometer and a condenser. The pH of the solution is adjustedto about 7.5 with KOH. Then a stream of nitrogen is introduced whichbubbles through the solution during the reaction. The solution isgradually heated to 65° C. Then MAPTAC (63.2 g) and octadecylmethacrylate (ODMA) (51.4 g) are introduced incrementally into the potwith vigorous stirring over a period of 5 hours so that the relativeconcentrations of the monomeric VP, MAPTA and ODMA monomer remainpractically constant throughout the reaction at predetermined levels.

As soon as MAPTAC and ODMA is introduced to the pot, Lupersol 11(t-butylperoxy pivalate in mineral spirits) catalyst is added. The rateof the addition of the catalyst is such that 2 ml of Lupersol iscompletely delivered in 4 hours. The solution is held for an additional3 hours at the 68° C. The product is an alcoholic solution of thehomogeneous terpolymer of VP, MAPTAC and ODMA.

180 g of the polymer solution then was transferred to a 2-liter flaskand 500 g of distilled water was added. The resulting solution then wasstripped under reduced pressure at 40°-50° C. on a rotovap to remove 200g of solvent (ethanol/water). A clear viscous polymer solution in waterwas obtained.

The sequence and mode of addition of monomers during the process issummarized in the Table below and the plot in FIG. 2.

                  TABLE                                                           ______________________________________                                        HOMOGENEOUS POLYMERIZATION OF VP, MAPTAC                                      AND ODMA                                                                      Time     VP      MAPTAC    ODMA    EtOH  Total                                (min)    (g)     (g)       (g)     (g)   (g)                                  ______________________________________                                        0        303.6   7.8       3.1     1001.0                                                                              1315.46                               0-30    0       13.2      10.3    0.0   1338.93                              30-60    0       11.9      10.3    0.0   1361.12                              60-90    0       10.0      8.6     0.0   1379.66                               90-120  0       8.0       6.8     0.0   1394.48                              120-150  0       6.3       5.1     0.0   1405.88                              150-180  0       4.7       3.7     0.0   1414.36                              180-210  0       3.5       2.6     0.0   1420.50                              210-240  0       2.5       1.8     0.0   1424.86                              240-270  0       1.8       1.2     0.0   1427.90                              270-300  0       1.3       0.8     0.0   1430.00                              Total    303.6   71.0      54.5    1001.0                                                                              1430.00                              % Wt     21.23   4.96      3.81    70.00  100.00                              % wt (t = 0)                                                                           23.08   0.59      0.23    76.10  100.00                              ______________________________________                                    

HAIR CARE PRODUCT

The homogeneous terpolymer of the invention contains a predetermineddominant blend of a hydrophilic part, i.e. VP/MAPTAC, and a smallproportion of a hydrophobic monomer, i.e. RMA. This homogeneousterpolymer composition enables the terpolymer to be readily adsorbedonto the negatively charged hair in high amounts as clear films, and toprovide both styling and conditioning functions, while still beingcapable of being readily rinsed or washed-off with water or shampooafter use.

In use in a water-based, rinse-off, hair styling and conditioningcomposition, the homogeneous terpolymer of the invention comprises about0.2-20%, preferably 1-10%, and, most preferably, about 2-8%, by weightof the hair care product, the rest being water, and, optionallyincluding an organic solvent such as ethanol, and/or other acceptableadjuvant components such as silicones, surface active agents, viscositymodifiers, dyes, chelating agents, distributing aids, pearlescent aids,opacifiers, perfumes, fatty alcohols, pH adjusting agents, and the like.

The homogeneous terpolymer of the invention finds particular utility inmultifunctional hair care products such as water-based, rinse-off hairstyling and conditioning products, and in leave-on hair care productssuch as a mousse, and may be included as a concentrate, or as a gel, andapplied as a self-actuated pump hair spray, or in an aerosol productwith a propellant. Various actuator and packaging devices known in theart may be used therewith.

While the invention has been described with particular reference tocertain embodiments thereof, it will be understood that changes andmodifications may be made which are within the skill of the art.Accordingly, it is intended to be bound only by the following claims, inwhich:

What is claimed is:
 1. A homogeneous terpolymer having dual hair stylingand conditioning properties for hair care use comprising by weight, (a)55-99% of a vinyl lactam, (b) 0.5-49% of a quaternary ammonium monomer,and (c) 0.5-49% of a hydrophobic monomer, which is made by homogeneouspolymerization of the monomers in a solvent in the presence of a radicalinitiator, which comprises:(a) precharging a reactor with apredetermined amount of the vinyl lactam, and solvent, at a suitablepolymerization temperature, and (b) introducing the quaternary ammoniummonomer and the hydrophobic monomer incrementally into said reactor at aspecific feeding schedule determined from the following Equations:##EQU3## where A_(t) has four adjustable parameters, a₁, a₂, a₃ and a₄ ;a₁ is a parameter which determines the center of the distribution; a₂ isa parameter which affects the width of the distribution; a₃ is aparameter which determines the ascending portion of the distribution;and a₄ is a parameter which determines the descending portion of thedistribution; and t=time (in minutes) from the beginning of thecopolymerization; ##EQU4## where N=time when the polymerization iscompleted: wherein a set of determined values for a₁, a₂, a₃ and a₄provides said specific feeding schedule and assures that the curve ofthe rate of disappearance of the vinyl lactam, during the polymerizationis substantially matched by the rate of disappearance for each of theslower reacting monomers, as shown in FIG. 2 herein.
 2. A homogeneousterpolymer according to claim 1 wherein (a) is vinyl pyrrolidone, (b) isa quaternary salt of an amino acrylamide or methacrylamide, an aminoacrylate or methacrylate, and (c) is a hydrophobic alkyl acrylate ormethacrylate, an alkyl acrylamide or methacrylamide.
 3. A homogeneousterpolymer according to claim 1 wherein (a) is vinyl pyrrolidone, (b) isa quaternized amino methacrylamide, and (c) is a C₄ -C₃₂ alkylmethacrylate.
 4. A homogeneous terpolymer according to claim 1 where (a)is vinyl pyrrolidone, (b) is 3-methacrylamidopropyl trimethylammoniumchloride, and (c) is octadecyl methacrylate.
 5. A homogeneous terpolymeraccording to claim 1 wherein (b) and (c) are introduced incrementally sothat all the monomers can react to form a substantially homogeneousterpolymer whose composition approaches the nominal monomer ratio of thedesired terpolymer composition.
 6. A homogeneous terpolymer according toclaim 1 wherein the solvent is alcohol.
 7. A homogeneous terpolymeraccording to claim 1 wherein said polymerization temperature is about50°-80° C.
 8. A homogeneous terpolymer according to claim 1 which alsoincludes the step of post-heating with additional radical initiator toreduce the residual VP content to <0.1%.
 9. A homogeneous terpolymeraccording to claim 1 wherein (a) is 65-95%, (b) is 0.5-40%, and (c) is0.5-15%.
 10. A homogeneous terpolymer according to claim 1 wherein (a)is 70-90%, (b) is 5-15%, and (c) is 1-10%.
 11. A homogeneous terpolymeraccording to claim 1 wherein (a) is 70-95% vinyl pyrrolidone, (b) is5-15% (3-methacrylamidopropyl) trimethylammonium chloride, and (c) is1-10% octadecyl methacrylate.
 12. A homogeneous terpolymer according toclaim 1 wherein the radical initiator is t-butylperoxy pivalate.
 13. Ahomogeneous terpolymer according to claim 1 wherein up to about 15% ofeach of (b) and (c) is included in the precharge.